1. Field of the Invention
This invention relates to an improved flashing system for cavity wall structures, and more specifically to metal foil/scrim Flashings suitable for through-wall and surface mounting installations.
2. Description of the Prior Art
In the past, investigations relating to cavity wall flashing systems for brick veneer masonry construction have been conducted. While strides have been made in flashing-related technologies, including metal foils, elastomeric materials and hot melt adhesives, there still remain several areas where continued development is ongoing.
The inventors' patents and their assignee's product line are all related to accessories for cavity wall structures and include insulation, anchoring and seismic devices, and masonry Flashings and are sold under the trademarks of Seismiclip®, Byna-Tie®, and DW-10-X®. These products, which are manufactured by Hohmann & Barnard, Inc., Hauppauge, NY 11788, have become widely accepted in the industry and have provided the inventors with particular insight into the technological needs of this marketplace.
Masonry walls with brick veneer are designed with an inner and an outer wythe and a cavity therebetween. The brick veneer outer wythe provides an aesthetic finish to the building, and the masonry block inner wythe and insulation thereon isolates the interior of the building from the environment. The walls of a building are constructed to exclude water and water vapor from the interior. Since the presence of excessive levels of water or water vapor in the cavity hastens the deterioration of building materials, various masonry flashing systems have been proposed.
Because of widespread usage and familiarity with bitumenous and asphaltic products in roofing applications, when masonry flashing systems were first designed, the building construction industry adopted the familiar copper and asphalt products. At that time the technology of pressure-sensitive hot melt adhesives needed for peel-and-stick applications was insufficiently developed. Some critics indicated that the adhesive quality was insufficient for the rough masonry block surfaces. Because of the presence of plasticizers, others were apprehensive about the available hot melt adhesives meeting the requisite fire retardancy standards. Also, to provide fire retardancy, some pressure-sensitive products were marketed for building construction use with inorganic fillers, such as alumina trihydrate, antimony oxide or calcium carbonate. However, these filled pressure-sensitive products had disadvantages, such as application problems, phase separation, toxicity, and reduced adhesion upon activation.
Prefabricated peel-and-stick flashing materials have been proposed, such as those shown in Harkness, U.S. Pat. No. 4,775,567 (see infra). These materials have included layers of bitumen and of bitumenous compounds for adhering the materials to the exteriors of masonry walls. While, under ideal circumstances, these peel-and-stick materials were easy to apply, the patent literature indicates that these materials did not conform well to irregular surfaces. Thus, the prior art bitumens used to secure these flashing materials to masonry walls often lacked the tackiness to bond tightly and durably to the wall surfaces. On occasion, when circumstances were not ideal, the bitumenous materials drooled marring the aesthetics of the brick veneer.
Scrim material has long been used as a reinforcement for bitumen-coated Flashings. The scrims developed in the past have been of polyester or fiberglass and structurally arranged as matted, nonwoven sheets or as open-weave fabrics. Such scrims are embedded in resinous or bituminous layers to reinforce the metal or elastomeric lamina of the flashing. The nonwoven scrims are described in U.S. Pat. No. 3,728,195 to Bolles and later in U.S. Pat. No. 4,762,744 to Woiceshyn et al. . Descriptions of various open-weave fabric scrims are found in the product literature of CCX, Inc., Walterboro, North Carolina 29488.
In the past, the previously mentioned assignee hereof has distributed, under the Copper Aqua Flash membrane name, a line of composite flexible Flashings. The composite, in one form thereof, is 50 mil. thick and consists of a 3-ounce, solid sheet of annealed copper laminated on one side to a polyester film and bonded on the other with a highly adhesive SBS modified bitumen (rubberized asphalt) with a peel-and-stick silicone top sheet. By completely encapsulating the copper in the polyester film on one side and rubberized asphalt on the other, the copper is protected from corrosion by alkaline or acidic solutions. Although the rubberized asphalt virtually eliminated the possibility of non-adhered areas, the Copper Aqua Flash membrane still had some of the previously described disadvantages of a bitumen-based flashing system.
Despite these early efforts, developing the right combination of materials and methods for flashing cavity walls in a fast and efficient manner has proved elusive. In addition to the above described technical problems, because there is frequently a delay in erecting the inner wythe and the outer wythe, the flashing installed in the inner wythe is often exposed to substantial ultra-violet radiation. Thus, standards similar to ASTM Specification G154 for nonmetallic materials need to be met by masonry flashing systems.
In preparing for this application the following patents came to the attention of the inventors and are believed to be relevant to the further discussion of the prior art:
U.S. Pat. No.InventorIssue Date6,224,700OakleyMay 1, 20016,035,582PacificMar. 14, 20005,870,864SnyderFeb. 16, 19995,860,259LaskaJan. 19, 19994,910,931PardueMar. 27, 19904,775,567HarknessOct. 4, 19884,762,744Woiceshyn et al.Aug. 9, 19884,755,409HarknessJul. 5, 19884,396,665RoweAug. 2, 19834,295,911Haage et al.Oct. 20, 19814,239,795Haage et al.Dec. 16, 19803,728,195BollesApr. 15, 1973
Oakley—U.S. Pat. No. 6,224,700—issued May 1, 2001
Oakley in U.S. Pat. No. 6,224,700 (assigned to Mar-Flex Systems, Inc., Middletown, Ohio) describes a method of applying a composite material to an above-grade building component to form a tacky non-swelling elastomeric membrane. Thereafter, a flexible, non-porous polymeric sheet is pressed onto the tacky exterior of the elastomeric membrane. The polymeric sheet is stronger than the elastomeric membrane and protects the elastomeric membrane from punctures or tears. Here, in situ construction is both labor intensive and requires special equipment for installation.
Pacific—U.S. Pat. No. 6,035.582—issued Mar. 14, 2000
Pacific describes a flashing material which includes a sheet layer of copper, aluminum or other metal or a thin sheet of unreinforced plastic. Here it appears that in situ adhesives are applied.
U.S. Pat. No. 5,870,864—Snyder—Issued Feb. 16, 1999
Snyder describes a drainage system employing water collection pans which for insertion into the interior cavities of masonry block units over the length of a selected block wall course for collecting the water drained through the interior cavities of the upper courses and directing water to the exterior of the wall.
U.S. Pat. No. 5,860,259—Laska—issued Jan. 19, 1999
Laska describes an insulated drainage panel for use in cavity wall or veneer wall construction which panel includes a planar insulating board with a porous structure thereof.
U.S. Pat. No. 4.910.931—Pardue—issued Mar. 27, 1990
In the Pardue patent, a water collection and drainage system is described for a masonry block wall having bond beam block courses and intervening standard block courses. A system of upper water collection pans is supported along each upper bond beam course. Downspouts leading from drain openings in the upper collection pans drain collected from the pans through the vertical block cavities in lower block courses to the next lower series of collection pans. Weeping spouts lead laterally from the base collection pans to the exterior of the wall to continuously drain collected water from the interior wall cavities.
U.S. Pat. Nos. 4,775,567 and 4,755,409—Harkness—issued Oct. 4, 1988 and Jul. 5, 1988, respectively.
A waterproofing laminate suitable for use in roofs, floors or other surfaces where waterproofing is desired contains a reinforcing sheet, first and second bitumen layers secured to opposite surfaces of the reinforcing sheet, first and second compound bitumen layers secured to the bitumen layers, an elastomeric sheet secured to the first compound bitumen layer and a release sheet secured to the second compound bitumen layer. Certain preferred materials for use in the laminate are recited.
U.S. Pat. No. 4,762,744—Woiceshyn et al. issued Aug. 9, 1988
A reinforcing composite for bitumen-installed roofing membranes is described. Here resinous adhesive impregnates the filament of the scrim without filling in the spaces therebetween so as to maintain the porosity of the scrim. Then, upon installation, the bituminous material mechanically fastens the treated mat-like scrim to the roof.
U.S. Pat. No. 4,396.665—Rowe—issued Aug. 2, 1983
This patent, assigned to W. R. Grace & Co., describes a pre-formed, pressure-sensitive, bituminous-type waterproofing membrane. Here, a scrim is an open-weave reinforcement material in the adhesive layer which is formed from a mixture of bituminous material and a synthetic rubber polymer.
U.S. Pat. Nos. 4,295,911 and 4,239,795—Haage et al.—Oct. 20, 1981 and Dec. 16, 1980, respectively.
A protective covering for the protection of surface seals against mechanical damage in building constructions and other civil engineering constructions which comprises a composite of an elastic, waterproof thermoplastic synthetic resin film sheet and/or synthetic resin layer and a lattice-like fabric having knot couplings or points of intersection of the threads that yield under the effect of a load.
U.S. Pat. 3,728,195—Bolles—issued Apr. 15, 1973
This patent describes the preparation of nonwoven fiberglass and of nonwoven polyester scrims. Additionally the scrims include machine-direction, continuous fiberglass filament reinforcement across the entire width. The scrims are in the 0.1 to 5 ounces per square yard (4 to 200 grams per square meter) range.
For through-wall installation, the masonry flashing of this invention includes a metal foil/scrim membrane with a resinous or adhesive coating thereabout. For through-wall and surface mounted installations, the masonry flashing includes, the metal foil/scrim, as just described, but having-on one surface thereof a pressure-activated hot melt adhesive and a release sheet. These membranes are designed to function cooperatively with drip plates and other accessories for brick veneer facing, and have been found to obviate the difficulties discussed while providing other advantages as set forth hereinbelow.